There are many situations in which it is desirable to provide a ramp from a vehicle or a loading dock to facilitate elevating heavy objects or vehicles. It is also desirable in some circumstances to provide a ramp that can be deployed and retracted so that it does not interfere with movement of the vehicle, or other uses of the loading dock, when loading using the ramp is not required.
According to the present invention, a deployable and retractable ramp assembly is provided which is reliable, relatively simple to operate, simple to construct, yet is sturdy enough to allow very heavy objects to be moved up and down the ramp when deployed, and when retracted is in a relatively low volume configuration, taking up a minimum amount of surface area. While the ramp assembly has many uses, in association with all types of vehicles, loading docks, and other structures, the invention is particularly applicable to use with a flatbed railroad car. When so utilized, the ramp assembly according to the invention may be used to facilitate loading and unloading of large pieces of railroad equipment (e.g. railroad maintenance or way equipment).
The basic assembly according to the present invention includes a plurality of ramp sections that are pivotally connected to each other; typically two or four sections are provided, with the last section pivotally connected to a support structure (e.g. railroad car), and the ends of the sections pivotally connected to each other in such a way that the ramp sections have a Z-folded configuration when retracted. By having a Z-folded configuration, the sections can deploy in segments, rather than in sequence, in a manner more suitable for ramp sections capable of supporting very heavyweights, and allows sturdy massive ramp sections to be retracted into a more compact position than if the sections were C-folded, or folded in another manner.
To facilitate deployment and retraction of the ramp sections, at least one mast, and preferably first and second masts, are provided, one mounted on each side of the ramp sections. Each mast has first and second sheaves mounted on a top end for cooperation with a cable; the cable moves from cooperation with one of the sheaves to cooperation with the other during deployment and retraction as the ramp sections move from one side of an upright position, overcenter to the other side of the upright position. The masts themselves may be pivotal with respect to a support structure, moved from an inoperative position into a substantially upright, operative position by a hydraulic cylinder connected to an arm engaging each mast, and the masts may be locked in their upright positions to prevent pivotal movement with respect to the support.
Deployment and retraction are necessarily mechanized because of the bulk and weight of the ramp sections. A winch and cable are preferably associated with each mast, and a third winch is provided connectable by a cable to cross braces of the second or fourth ramp sections to provide a restraining force to the ramp sections to prevent them from moving too rapidly under the force of gravity once moved to an overcenter position.
The ramp sections may be locked in place; typically the second and third sections are locked to each other once they are moved in-line. The other sections need not be locked with respect to each other since they unfold into positions in which they abut each other, so that they will not pivot with respect to each other under the force of gravity. Guide wheels may be connected to the free ends of the first section tubes or rails to facilitate movement of the first ramp section along railroad tracks to make deployment easier.
According to one aspect of the present invention, a deployable and retractable ramp assembly is provided comprising the following elements: Two Z-folded ramp sections, comprising first and second sections each having first and second ends, the second end of the first ramp section pivotally connected to the first end of the second ramp section. A first mast having a first end and a second end, the second end having first and second sheaves mounted thereon. A first cable connecting element mounted to at least one of the ramp sections, for connecting a cable end thereto. A first cable dimensioned to operatively engage either of the sheaves, and having a first, free, end adapted to be connected to the first cable connecting element; and first power means connected to a second end of the first cable for selectively deploying or taking up the cable, to power the ramp sections to move from a stacked, Z-folded first position to an unfolded, substantially in-line second position, and vice-versa.
Preferably the ramp assembly comprises four Z-folded ramp sections, a third ramp section pivotally connected at a first end thereof to an end of the second ramp section opposite the first ramp section, and a fourth ramp section pivotally connected at a first end thereof to a second end of the third ramp section. The assembly also preferably further comprises a second mast having first and second ends with first and second sheaves mounted to the second end thereof; a second cable connecting element connected to at least one of the ramp sections; a second cable dimensioned to operatively engage either of the sheaves of the second mast, and having a first, free, end adapted to be connected to the second cable connecting element; and second power means connected to a second end of the second cable for selectively deploying or taking up the cable, to, with the first power means, power the ramp sections to move from a stacked, Z-folded first position to an unfolded, substantially in-line second position, and vice-versa; the first and second masts mounted on opposite sides of the ramp sections. The ramp sections each may comprise first and second 6.times.12 inch rectangular tubes, or railroad rails spaced from each other by cross braces the same distance as the spacing of railroad car wheels on a common axle, and the fourth ramp section may be pivotally mounted to a flatbed railroad car.
According to another aspect of the present invention, there is provided a railroad car for mechanized loading and unloading of maintenance of way equipment therefrom. The railroad car comprises: A substantially flat load-carrying surface of the railroad car, and a plurality of railroad car wheels, on axles, supporting the load-carrying surface. And a deployable and retractable ramp assembly mounted to the railroad car and when in a deployed position providing a ramp for the movement of maintenance of way equipment from railroad tracks to the railroad car, or vice versa. The assembly comprises: two Z-folded ramp sections, comprising first and second sections each having first and second ends, the second end of the first ramp section pivotally connected to the first end of the second ramp section; the ramp sections each comprising first and second rectangular tubes or railroad rails spaced from each other by cross braces the same distance as the spacing of railroad car wheels on a common axle; and means mounted on the railroad car for effecting powered pivotal movement of the first and second ramp sections with respect to each other to be deployed in a position in which the first and second ramp sections are substantially in-line and maintenance of way equipment on a railroad track may move up the tubes or rails of the ramp sections to the railroad car, and a retracted position in which the ramp sections are Z-folded and rest on the railroad car load-carrying surface.
The railroad car further preferably comprises a fossil fuel powered engine mounted on or adjacent the load-carrying surface; and the means for effecting powered pivotal movement of the ramp sections preferably comprises electric or fluid or both motors, the motors ultimately powered by the fossil fuel powered engine. Preferably three hydraulic winch motors and two hydraulic cylinders are provided.
According to a still further aspect of the present invention, an assembly for mechanized deployment or retraction of a ramp is provided which comprises: A support for the ramp. A plurality of ramp sections pivotally connected to each other at the ends thereof, and one of the ramp sections pivotally connected to the support. First and second masts each having a first end pivotally connected to the support for pivotal movement about a pivot axis, and a second, free end with at least one sheave mounted thereon. Means for moving the masts about the pivot axes from a first, inoperative, position generally along the support to a second, operative, position upstanding from the support. Means for selectively locking the masts in the second positions to preclude pivotal movement of the masts about the pivot axes when in the second positions; and first and second cables passing in operative association with the first and second mast sheaves, respectively, and having free ends thereof connectable to one or more of the ramp sections. The masts each have first and second sheaves mounted on the second ends thereof, the first and second cables dimensioned to cooperate with the sheaves.
According to a still further aspect of the present invention, a method is provided of deploying and retracting a ramp. The ramp has first and second Z-folded ramp sections, the first section having a free first end and a second end pivotally connected to the first end of the second ramp section, and the second end of the second ramp section pivotally connected to another structure, utilizing an upstanding mast having a free end with first and second sheaves mounted thereon, and a cable having a free end and dimensioned to cooperate with the sheaves. The method comprises the steps of: (a) Passing the cable around the first sheave, and connecting the free end thereof to the second ramp section. (b) Applying a first force, in a first direction, to the cable to move the free end of the cable toward the first sheave, causing the ramp sections to lift up to substantially an upright position as the second ramp section pivots about its pivotal connection to another structure. (c) Continuing to apply the first force to the cable causing the free end of the cable to move toward the first sheave until the ramp sections move past the upright position, and the first ramp section, under the force of gravity, starts to pivot away from the second ramp section, while applying a restraining force to the second ramp section to prevent the ramp sections from falling too rapidly past the upright position after passing past the upright position. (d) Once the ramp sections have moved to a position in which further application of the first force does not further deploy the ramp sections, terminating application of the first force to allow the cable to move into operative association with the second sheave, and so that the ramp sections continue to move under the force of gravity so that the first and second sections pivot with respect to each other until the first and second sections are substantially in-line, abutted against each other; and then (e) disconnecting the cable from the second ramp section.
The ramp also preferably includes third and fourth ramp sections, the third ramp section first end being the other structure to which the second ramp section is pivotally connected, and a second end of the third ramp section pivotally connected to a first end of the fourth ramp section, so that the ramp sections are all Z-folded with respect to each other, with the fourth ramp section pivotally connected at a second end thereof to yet another structure; and wherein the second and third sections are substantially in-line with each other when step (e) is practiced. The method then also comprises the further steps of: (f) After step (e), connecting the cable free end to the fourth ramp section, the cable in engagement with the first sheave, and locking the second and third ramp sections together in substantially in-line position. (g) Applying the first force to the cable again to elevate the fourth ramp section while the third and fourth ramp sections pivot with respect to each other and the first, second and third sections move away from the fourth section, until the fourth section reaches substantially an upright position. (h) Continuing to apply the first force to the cable causing the free end of the cable to move toward the first sheave until the fourth ramp section moves past the upright position, while applying a restraining force to the fourth ramp section to prevent the fourth ramp section from falling too rapidly past the upright position after passing past the upright position. (i) Once the fourth ramp section has moved to a position in which further application of the first force does not further deploy the ramp sections, terminating application of the first force to allow the cable to move into operative association with the second sheave, and so that the ramp sections continue to move under the force of gravity so that the third and fourth sections pivot with respect to each other while the fourth section pivots with respect to the yet another structure until the third and fourth sections are in line with, and abut, each other; and (j) disconnecting the cable from the fourth ramp section.
The method also preferably comprises the further step (k) of reinforcing the ramp sections adjacent the pivotal connections between the second and third, and third and fourth sections by supporting them off the top of a railroad rail. The method also preferably comprises the further steps of retracting the ramp sections by practicing steps (j)-(a) in reverse but applying a second force in a second direction, opposite the first direction, in place of where gravity is the moving force in steps (a)-(j), and wherein gravity, counteracted by a restraining force to prevent too rapid a movement, takes the place of the first force in steps (a)-(j).
It is the primary object of the present invention to provide for the effective loading and unloading of objects or vehicles, regardless of weight, using a deployable and retractable simple but sturdy ramp assembly. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.